In June, Chai Mishra launched Movebutter, a small online grocery store with 300 products that promised shoppers more curated and high-quality choices than major grocery stores, which stock as many as 50,000. A month and a half later, the company had a waiting list of 120,000 people who wanted to place orders on its website.

Movebutter is one of dozens of grocery and food brands aiming to grab their own chunk of the $627 billion Americans spent last year on groceries, per YouGov. Online grocers accounted for $12 billion of those sales, and 27 percent of U.S. adults said they’ve shopped from an online supermarket. Big retailers like Kroger, Walmart, Albertson’s and Costco dominate 40 percent of the market. And that’s where challenger brands see an opportunity to shake things up.

With new business models and unique offerings, brands like Brandless, Thrive Market, HelloFresh and Halo Top are challenging traditional packaged-goods brands and retailers.